In a video encoder of the related art that compresses and transmits video, an uncompressed digital video signal such as 3G-SDI, HD-SDI, or SD-SDI is input, compressed using compression technology such as MPEG-2, 11.264, or JPEG 2000, and the compressed data is stored in MPEG-2 TS format and transmitted over DVB-ASI or Ethernet (registered trademark). In addition, in a video decoder of the related art, the data is received over DVB-ASI or Ethernet, which has been stored in MPEG-2 TS format and compressed using compression technology such as MPEG-2, and the compressed data is decoded and output as an uncompressed digital video signal such as 3G-SDI, HD-SDI, SD-SDI, or HDMI (registered trademark).
Regarding transmission of IP packet stream over Ethernet and reception of IP packet stream over Ethernet, video encoders and video decoders that transmit and receive using a packet format and forward error correction (FEC) scheme conforming to the SMPTE 2022-1/2 specification standardized by the Society of Motion Picture and Television Engineers (SMPTE) are increasing.
FIG. 1 includes diagram illustrating a video encoder of the related art. The video encoder 100 illustrated in FIG. 1 includes an HD-SDI input interface unit 101, an encoder control unit 102 that outputs video data and audio data from an input HD-SDI signal, an H.264 video encoder 103 that compresses and encodes retrieved video data, an AAC audio encoder 104 that compresses and encodes retrieved audio data, an MPEG-2 TS generator 105 that generates an MPEG-2 TS in which the compressed and encoded video data and the compressed and encoded audio data are multiplexed, a signal conversion unit 106 that IP packetizes the compressed video signal, and an IP output interface 107 that outputs a IP packet stream 120 of compressed video.
The video encoder 100 receives an HD-SDI uncompressed digital video signal 110 from a coaxial cable 111 with the HD-SDI input interface unit 101, compresses the video data with the H.264 video encoder 103, and compresses the audio data with the AAC audio encoder 104. Next, the compressed video and audio data is stored and multiplexed in MPEG-2 TS format by the MPEG-2 TS generator 105, IP packetized by the signal conversion unit 106, and an IP packet stream 120 of compressed video conforming to the SMPTE 2022-1/2 specification is transmitted from the IP output interface 107 over a 1 Gbps Ethernet 121.
FIG. 2 is a configuration diagram illustrating a video decoder of the related art. The decoder 200 illustrated in FIG. 2 includes an IP input interface unit 201, a signal extraction unit 202 that retrieves an MPEG-2 TS from an input IP packet stream, a decoder control unit 203 that outputs compressed video data and compressed audio data from the MPEG-2 TS, an H.264 video decoder 204 that decompresses and decodes the retrieved video data, an AAC audio decoder 205 that decompresses and decodes the retrieved audio data, an audio embedding unit 206 that generates an uncompressed video signal from the decompressed and decoded video data and audio data, and an HD-SDI output interface unit 207 that outputs the uncompressed video signal as an HD-SDI video signal.
The video decoder 200 receives an IP packet stream 210 of compressed video from a 1G Ethernet 211 with the IP input interface unit 201, and with the signal extraction unit 202, retrieves an MPEG-2 TS from the input IP packet stream 210. In the decoder control unit 203, the MPEG-2 TS extracted with the signal extraction unit 202 is separated into compressed video data and compressed audio data. The compressed video data and the compressed audio data is decompressed and decoded by the H.264 video decoder 204 and the AAC audio decoder 205, respectively. Next, in the audio embedding unit 206, the audio data is embedded into the decompressed and decoded video data to generate an uncompressed video signal, and the uncompressed video signal 220 is transmitted from the HD-SDI output interface unit 207 over the coaxial cable 221.
A video encoder that receives an uncompressed video signal such as 3G-SDI, HD-SDI, or SD-SDI is often used by being connected to a camera at a stadium or the like, or used when processing video inside a broadcasting station. Consequently, convenience of operation is important, and the above video encoder is convenient in that by simply connecting a coaxial cable carrying an uncompressed video signal to the input, a DVB-ASI signal carrying a compressed video signal may be obtained on the output coaxial cable, or a compressed video signal stored in the SMPTE 2022-2 format may be obtained on the output Ethernet.
However, regarding the video signal, only one data stream or one pair of data streams (in the case of 3G-SDI Level-B) is sent on one coaxial cable or optical fiber cable. For this reason, in a system in a broadcasting station or the like that handles multiple video data streams, it is necessary to install a number of video encoders proportional to the number of video data streams, or install a switching device such as a matrix switcher for selecting a video signal to input into the video encoder from among multiple uncompressed video signals. Likewise, for the video decoder, it becomes necessary to provide a number of video decoders proportional to the number of video data streams, as well as a switching device such as a matrix switcher for selecting the uncompressed video signal to use inside the broadcasting station from among the multiple uncompressed video signals output from these video decoders.
FIG. 3 is a diagram illustrating a video delivery system 300 provided with a number of video encoders of the related art in proportion to the number of video data streams. FIG. 4 is a diagram illustrating a video delivery system 400 provided with a matrix switcher. Both FIGS. 3 and 4 illustrates systems that collect video from a large number of arenas at a broadcasting center, and after compressing the video with video encoders, transmit the video to a broadcasting station.
In the system 300 of FIG. 3, video encoders 322-1 to 322-99 are includes in the broadcasting center 320 in order to encode each video from stadium 310-1 to 310-10. The videos compressed by the video encoders 322-1 to 322-99 are input into a video transmission unit 323, and in the video transmission unit 323, a specific video is selected, processed, and sent over an external network.
In the system 400 of FIG. 4, the matrix switcher 424 selects video signals to input into video encoders 422-1 to 422-2 from among video signals from stadiums 410-1 to 410-10. The videos compressed by the video encoders 422-1 to 422-2 are input into a video transmission unit 423, and after being processed, are sent over an external network.
An uncompressed video signal such as 3G-SDI, HD-SDI, or SD-SDI is ordinarily transmitted using coaxial cable. However, there is a distance limitation on the transmission of a video signal using coaxial cable. Therefore, in order to transmit the video signals of the stadiums 310-1 to 310-10 or 410-1 to 410-10 to the broadcasting center 320 or 420, equipment that converts an electrical signal into an optical signal is used, and the optical signal is transmitted over optical fiber cable. In FIG. 3, HD-SDI video signals output by cameras 311-1 to 311-99 are converted from electrical signals to optical signals using LID (electrical-to-optical) converters 312-1 to 312-99, transmitted over optical fiber, and at the broadcasting center 320, converted again from optical signals to electrical signals using O/E (optical-to-electrical) converters 321-1 to 321-99. Similarly, in FIG. 4, HD-SDI video signals output by cameras 411-1 to 411-99 are converted from electrical signals to optical signals using E/O converters 412-1 to 412-99, transmitted over optical fiber, and at the broadcasting center 420, converted again from optical signals to electrical signals using O/E converters 421-1 to 421-99.
Also, FIG. 5 is a diagram that illustrates a broadcasting station system 500 includes a number of video decoders of the related art in proportion to the number of video data streams, and illustrates a system that receives video from an external stadium or another broadcasting station, and delivers the video to an editing system, transmission system, and monitor group inside the broadcasting station.
In the system of FIG. 5, video from cameras 511-1 to 511-99 of arenas 510-1 to 510-10 is encoded inside each stadium using video encoders 512-1 to 512-99, and sent to the broadcasting station 520 via a 1 Gbps Ethernet. Compressed video from other broadcasting stations 531 and 532 is similarly sent to the broadcasting station 520 via the 1 Gbps Ethernet. The broadcasting station 520 is provided with video decoders 522-1 to 522-101 for decoding IP packet streams of compressed video received over the above 1 Gbps Ethernet. Each HD-SDI uncompressed video signal including video data decoded by the video decoders 522-1 to 522-101 is input into a matrix switcher 521. HD-SDI uncompressed video signals required by an editing system 524, a transmission system 525, and a monitor group 523 are selected by the matrix switcher 521, and output to the respective systems and the monitor group.
In this way, with the technology of the related art, in a sports broadcast system that broadcasts by switching video from multiple stadiums depending on the time, or a system that selects and compresses multiple video signals selectively from among a large number of uncompressed video signals, such as an internal distribution system of a broadcasting station that receives and distributes a large number of videos from outside sources, it is necessary to prepare video encoders individually for all uncompressed video signals in advance, or place a matrix switcher for video signals near a video encoder and switch the video to be encoded.
Additionally, in a system that receives video from multiple stadiums or other broadcasting stations and distributes the video in a broadcasting station, in order to link up with an uncompressed video signal processing system using coaxial cable in the broadcasting station, it is necessary to prepare video decoders individually for each IP packet stream received externally, and use a matrix switcher for video signals to select the signal required by each system in the broadcasting station from among the uncompressed video signals output by these video decoders.
With these systems, it is often necessary to install inactive equipment as illustrated in the example of FIG. 3, or in other words, video encoders must be prepared even for video from stadiums where broadcasting is not being conducted. At sports events such as the soccer World Cup and the Olympics, it is clearly unrealistic to reorganize the equipment according to the day-to-day competition schedule.
One method of reducing the number of inactive equipment is to take a configuration as illustrated in FIG. 4. However, the configuration in FIG. 4 requires the preparation of an extremely costly matrix switcher. Furthermore, the number of selected videos is limited by the number of physical ports on the matrix switcher, and there is a problem in that system flexibility is lost.
Furthermore, the system configuration in FIG. 5 requires the preparation of both a large number of video encoders and a matrix switcher, and system flexibility is also lost.
Another problem in the case of using the technology of the related art is the cost of constructing the transmission lines. As illustrated in FIGS. 3 and 4, converting a video signal from an electrical signal to an optical signal and then from an optical signal back to an electrical signal incurs the costs of purchasing and installing dedicated equipment. Furthermore, dedicated optical fiber service provided by a communications carrier under the name of dark fiber or the like incurs enormous service fees depending on the country. With these systems designed for coaxial cable, there is also a problem in that laying cable is laborious, and running cable in a broadcasting station or the like incurs enormous costs.
On the other hand, with recent advances in IT technology, broadcasting systems are transitioning to an Internet Protocol (IP) base. This trend is described in, for example, “Broadcasting Facilities and Operations”, Journal of the Institute of Image Information and Television Engineers, Vol. 67, No. 5 (2013). IP-based systems are also coming to be used in video delivery systems. In these IP-based broadcasting systems, video signals are IP packetized and transmitted using the Real-Time Transport Protocol (RTP). Consequently, making a broadcasting system IP-based requires video encoders and video decoders designed to be used on an IP network.
However, encoders of the related art only receive an uncompressed digital video signal such as HD-SDI, store data compressed using compression technology such as H.264 in MPEG-2 TS format, and transmit the compressed data over Ethernet, like the encoder discussed earlier and illustrated in FIG. 1. Consequently, an encoder of the related art is unable to compress and encode uncompressed video until after an IP packet stream of uncompressed video goes through a process of being converted to an uncompressed digital video signal such as BD-SDI first.
In addition, video decoders of the related art can only receive data that has been stored in MPEG-2 TS format and compressed using compression technology such as MPEG-2 over Ethernet or the like, decode the compressed data, and output the result as an uncompressed digital video signal such as HD-SDI, like the video decoder illustrated in FIG. 2. Consequently, a decoder of the related art is only able to output decompressed digital video signal such as HD-SDI, then the output of the decoder is unable to deliver to IP network directly.
However, conducting IP/HD-SDI signal conversion first in this way requires a video transmission device that conducts IP/HD-SDI signal conversion in addition to the encoder or decoder, and the number of pieces of equipment increases.